The term area 31a refers to a part of posterior cingulate cortex located caudally in the posterior cingulate gyrus. It is bounded caudally by area 31pd, dorsally by area 23c, rostrally by area 23d and ventrally by area 31pv. It is considered one of three parts of area 31 of Vogt-2009. The others are area 31pv and area 31pd. Defined in the human by multiple criteria, it is fMRI-activated in BODY, FACES, PLACE, and THEORY OF MIND tasks. It is deactivated in FACE and LANGUAGE tasks. Other authors have referred to overlapping parts of the same topological area as 31, 31d and 31v ( Glasser-2016 ).